Fig 1.
The optimized photography set-up for imaging mice.
(A) The photography set-up. In a laminar flow cabinet with dual opening (a), illuminated by two additional fluorescent lights on the side (b), mice were placed one at a time on a frosted glass plate with a broad-grid fabric tape that was positioned above black paper and two scale bars (c). The remote shutter controlled camera (d) was positioned 130 mm above the glass plate on a telescopic support (e). (B) Representation of the imaging set-up with distances. The camera lens (O) was placed 130 mm above the glass plate, which resulted in a height difference of 26 mm between the scale bar below the glass plate (BD) and tumor (AC) on the dorsal skin of the mouse from the camera lens. The length or width dimension of the tumor (AC) was calculated using Thales’ theorem to determine the scale factor of OA/OB = 0.8 = AC/BD. Since tumors were distributed broadly over the dorsal skin of the mouse, each tumor was carefully calibrated against the nearest portion of the scale bar for better accuracy of measurement. For example, the tumors in EC region of the skin were calibrated against FD segment of the scale.
Fig 2.
Measurement of tumor dimensions and total tumor burden in mice by two methods.
(A) Top and profile view pictures of a mouse with multiple UVB-induced skin cancers for photographic method of measuring tumor dimensions. The top views of the mouse with scale bars (top image) were used for detecting tumors (incidence) and for counting the tumors to determine the multiplicity. The magnified images of individual tumors from top view, as shown here for tumors # b and c, were used for measuring the length and width of tumors. The profile pictures of the mouse (bottom images) allowed measurement of heights of all tumors, as shown here for encircled magnified images of these two tumors in different profile images. The calibration of pixel to distance in profile pictures was achieved by comparing either the length or width dimension of a given tumor in both top and profile magnified images. The newly calibrated pixel distances in profile picture now allowed accurate measurement of height of this tumor in profile images. The cysts such as the one seen between eyes were identified as described in the caliper method were excluded in tumor counts. (B) Comparison of time-course of increasing total tumor burden (area) in mice as measured by the caliper and photography methods. The total tumor burden (area) in three different mice was monitored from 20 to 25 weeks of the protocol by caliper and photography methods.
Table 1.
Comparison of tumor volume and area of 30 tumors by caliper and photographic methods.
Table 2.
Comparison of total tumor burden on 6 mice using photographic and caliper methods.
Table 3.
Accuracy and precision of the photography and caliper methods.